RPM reading on Pscan

RPM reading on Pscan was created by Happy MGF user

Posted 1 year 2 months ago #202175
Car does not start have small spark on plug Pscan mostly missing RPM it comes some times but not at all times mostly not. All ideas are good I am looking for a way out to start the car change of crank sensor cleaned wires etc have not found the problem other then I have RPM that does not come up if it comes then it is at about 250RPM with plugs out turing engine.

Need help

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Replied by Airportable on topic RPM reading on Pscan

Posted 1 year 2 months ago #202176
Happy MGf User implies an early car, are you pre or post Y2k & which engine. Is it a 160 / 145 VVC, a 135 or a115, all the variants are configured in different ways & to home in on your problem requires that bit more info.
Having made the first move on this I'll not be able to follow it up as I'm away for a couple of weeks & although I'll be looking in there'll be little chance in contributing. However this should be slap bang in Our Man from Down Under's territory,he should be along shortly, he's probably got distracted playing with his Didgeridoo. Let's hope he's wiped his hands.
Last Edit:1 year 2 months ago by Airportable
Last edit: 1 year 2 months ago by Airportable.

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Replied by Happy MGF user on topic RPM reading on Pscan

Posted 1 year 2 months ago #202177
Hi the car is a MGF 1.8 MPi MEMS 1.9 from 1999 LF
I did something I pulled fuse 12 and set a different car battery to this on the out going side of the fuse. 12 volt in with ground form the extra battery to the chassy I did this to se if I could make the Pscan stable during cranking of the engine and not fall out. This as I believed that Diagnose out lett had power from fuse 12. I measured amps over the fuse before and read 1,5 to 1,7amp. After connecting to the fuse out with the separate car battery the amp came up to 2,5-2,7 amp fot well light stronger and Pscan worked during cranking of the engine. Live data came up 2 times with Rev on the RPM on Pscan live. First time. I am no longer sur if it was power problem on diagnose socket or the the ECU was glad not to supply power to Pscan? I now believe the crank sensor works as I have spark and RPM reading.But it may also be wires. I have also bolted out the 2 wires from ECU / relle ground. from the aft of the engine room and connected them with a wire to battery minus.direktly just to make sure I have ground.

I have fuel pressure I have timing of engine I have spark not a big one as I have now pulled the plugs and turned the engine on the starter to fra if the crank sensor worked. the gas smells up the garage so I believe I have fuel. Problem started with the car stopped during driving. I believed I had managed to drive empty of gas but NO, Change fuel pump no change no start and purchased P scan the Pscan reported crank sensor. Crank sensor changed. BUT during the hole time I have had spark small but spark, mounded fuel pressure gauge it does not come up to 3 bar stops at 2,6-2,7 bar I can hold back on the return hose and bust the pressure but I believe I may damage the system. May the rotor aksel have moved that drives the spark? I have installed new plugs and order new rotor cap and leads but the car stop during driving so plugs and leads are not the normal thing.Fuel yes engine timing Yes valves meeting pistons ... engine has compressing 175 on 1 and 4 and 200 on 2 and 3. I do not have spark on cylinder no 2 but i believe it should start. Need more ideas. I must have missed something. that I got the RPM on Pscan by adding Power to the fuse May be that crank sensor now does work but no start.

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Replied by Happy MGF user on topic RPM reading on Pscan

Posted 1 year 2 months ago #202178
Also as I remove the ground on the battery and had the ground wire to the ECU off and on the stepper motor sound came. this as if the ECU ran the stepper ready for start.
I am not sure regarding the RPM but with the battri power on the fuse 12 I did have RPM.

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Replied by Cobber on topic RPM reading on Pscan

Posted 1 year 2 months ago #202181
No spark at #2 is a problem that needs fixing even if it runs.
Now you say that you have a distributor cap and plug leads on order, have you also ordered a new distributor rotor arm?
If not do so. Unlike conventional distributors the ones used don’t have all that much going on inside, the rotor arm is secured directly to the end of the camshaft spigot (dee sectioned) by a screw, this is @ 180 degrees opposite the rotor tip, make sure it’s tight and the rotor isn’t free to move about on the shaft.
Could you please take pix of the rotor arm and distributor cap both inside and outside of the cap, and post them on here so we can help you diagnose the problem.

There is one other highly unlikely but theoretically possible scenario.
Check the runout of the end of the camshaft with the distributor removed if it’s running eccentric (a bit like a cam itself as opposed to a running in a true rotational shaft pattern….smooth) then that will be a problem.
Unfortunately due to the dee section profile of the spigot on the camshaft end this will be difficult ( normally you would use a dial gauge for this ) you will have to eye ball this whilst a glamorous assistant rotates the crankshaft by hand….Tip, remove the spark plugs to make turning easier and smoother.
Another indicator of excessive runout might be evidence of oil leaking past the oil seal on the cam shaft end.
Any excessive runout that would be a problem will probably be visible with the eye.
The cause for this could be camshaft journal and bearing surface wear due to a lack of lubrication the the cyl head, possibly by running with low oil level or a blockage in the oil feed gallery feeding the cyl head.
I did say that this is highly unlikely, but it would be a real ball ache to fix.
If there is such a problem then the reason it will runout is because when a cam loads up against the valve gear it will try and lift the camshaft in that location and if the is excessive play in the support of the camshaft then that will translate as runout causing the distributor rotor to rotate in an eccentric manner, possibly missing #2 of the distributor cap.
I must point out that in the MG engine rebuild section of the manual they make no mention of this, so obviously they didn’t anticipate this as being a problem, they do mention measuring camshaft endfloat but not runout.
The fact that they hadn’t foreseen this problem doesn’t mean it isn’t a possibility, but it does make it unlikely.


Until you’ve dealt with these, you’ll probably not be able to start the car or make it drivable , but there are still plenty of things you can and should do in the meantime.

Go over all electrical connections in the engine bay, make sure the is no corrosion or verdigris ( green or blueish green powdery shit) on any of the terminals, both the terminals in the wiring plugs and on the various components.
Is the wiring still supple? In particular close to the terminals, and is there any damage to the insulation?
These engines live in a very hot environment and the wiring can get a bit cooked and brittle.
Anything suspect should be dealt with.

How are all of the fuses and fusible links any signs of corrosion or verdigris on the terminals of the fuse box and fuse.
The terminals of the fuse box will need to be cleaned, just replace any dirty fuses or fusible links.
Even if any of the problems found here aren’t the cause of your starting problems, they will need fixing anyway to ensure your continued enjoyment of the car.

To sum up, go over all the electrical connections, fuses etc. take some happy snaps of the old dizzy cap and rotor to post here for our perusal, replace the parts with those ordered and if you can be arsed check for excessive runout.

Once you’ve done that lot, get back to us with the results, if it’s still being a pain it the arse we’ll get all diagnostic on it’s sorry arse!

"Keep calm, relax, focus on the problem & PULL THE BLOODY TRIGGER"

Last Edit:1 year 2 months ago by Cobber
Last edit: 1 year 2 months ago by Cobber.
The following user(s) said Thank You: Happy MGF user

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Replied by Happy MGF user on topic RPM reading on Pscan

Posted 1 year 2 months ago #202186
New Parts in place I did change the rotor but did this before I read the answer After some testing with start cables grounded tom the battery I hade spark on all but not a good one. I have order up a coil now.I do have problems with steady spark have changed spark plugs etc. I will take off the new cap and try the rotor if it turns in a circle.

But I used the blink lamp on spark lead no1 and the spark flashes almost 170 degree after TDC Not 10 degree before. It may be the blink lamp on the new leads but.. Can the crank sensor read wrong on the fly wheel?

Thanks for input. I will try with some Photos But somfare the new parts did not help.

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Replied by Happy MGF user on topic RPM reading on Pscan

Posted 1 year 2 months ago #202188
I am trying to add photos now
Last Edit:1 year 2 months ago by Happy MGF user
Last edit: 1 year 2 months ago by Cobber. Reason: Added pix

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Replied by Happy MGF user on topic RPM reading on Pscan

Posted 1 year 2 months ago #202189
I had some issues with getting the photos in but it looks like it worked. Please se the marking on the cranck shaft I have put the engine in the spot were the blink lamp on the lead shows blink on cylinder 1 it is fare from 10 degree before TDC But it may be the lamp on the new leads? How is it to be?

Thanks. PS i had cleaned and sprayed the old cap and the rotor no change. But I shall try the offsett of the rotor.

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Replied by Happy MGF user on topic RPM reading on Pscan

Posted 1 year 2 months ago #202190
I added a photo to how I added power to fuse 12 to make the Pscan work during crancing of the engine. This from a different car battery. Ekstra Batteri also added to the ground chassis. This works for the Pscan for me.

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Replied by Happy MGF user on topic RPM reading on Pscan

Posted 1 year 2 months ago #202191
PS no start of the car. Can the rotor shaft have moved in the camshaft? or is it the crank shaft sensor giving wrong signals? There is a lot of life from the coil but... May I have the spark in the wrong place, but the camshafts line up according to the crank shaft at middle mark. all cylinders in middle point.

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Replied by Happy MGF user on topic RPM reading on Pscan

Posted 1 year 2 months ago #202193
Ok lead and cap off, plugs out. After some ajustment to the mesuring clock on the platick new rotor out on the end. and yes flash plastik plate off. Bolt fixed. I will try to add the film and photos.
Last Edit:1 year 2 months ago by Happy MGF user
Last edit: 1 year 2 months ago by Cobber.

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Replied by Happy MGF user on topic RPM reading on Pscan

Posted 1 year 2 months ago #202194
Messured on plastic on the aft of the new rotor I had more then about 1/2 to 3/4 turn in the dail I do not know if that is good or bad. there is offsett due to that it is on a shaft and pulled by the bolt to one side it does not look like it is the shaft. but the shaft may have turned I do not know all ideas are good for me now.

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